Django atomic transactions for data integrity

                  from django.db import transaction
from django.http import JsonResponse


@transaction.atomic
def transfer_funds(request):
    """Transfer money between accounts atomically."""
    from_account_id = request.POST['from_account']
    to_account_id = request.POST['to_account']
    amount = Decimal(request.POST['amount'])

    from_account = Account.objects.select_for_update().get(id=from_account_id)
    to_account = Account.objects.select_for_update().get(id=to_account_id)

    if from_account.balance < amount:
        raise ValueError('Insufficient funds')

    from_account.balance -= amount
    to_account.balance += amount

    from_account.save()
    to_account.save()

    # Create transaction record
    Transaction.objects.create(
        from_account=from_account,
        to_account=to_account,
        amount=amount
    )

    # If anything fails above, all changes roll back
    return JsonResponse({'status': 'success'})


def create_order_with_items(order_data, items_data):
    """Create order and items in one transaction."""
    with transaction.atomic():
        order = Order.objects.create(**order_data)

        for item_data in items_data:
            OrderItem.objects.create(order=order, **item_data)

        # Send email only if transaction succeeds
        transaction.on_commit(lambda: send_order_email.delay(order.id))

    return order